A lighting device is commonly used to improve a space of dim light or a location where light is shielded for ensuring sufficiency of lighting and protecting eyes against poor eyesight or eye diseases, such as myopia, caused by long term insufficiency of lighting. Further, the trend of energy saving and carbon reduction and the invention of light-emitting diodes (LEDs) cause the traditional light sources of tungsten filament bulbs, which consume a large amount of power, to be gradually replaced by LEDs, which are of a small size and consume a minor amount of power.
A conventional lighting device is often composed of a circuit board, a base, and a hood. The circuit board carries a plurality of LEDs mounted thereon and is fixed on the base. The base and the hood are coupled to each other. The circuit board comprises a circuit that controls the operation of the light-emitting elements to give off light. However, the base must be pre-machined through tapping operation to form inner-threaded holes therein. The circuit board is then fixed to the base by being secured by bolts that are tightened to the inner-threaded holes one by one. This operation is troublesome. Further, the bolts are tightened in a one-by-one manner and a large number of bolts are used in securely fixing the circuit board. This often leads to unbalance distribution of tightening force and warp and deformation of the circuit board.
Further, since the operation of multiple LEDs generates a great amount of heat, the conventional lighting device is often provided with a heat dissipater on the circuit board to remove the heat generated by the multiple LEDs. However, the conventional heat dissipater is made of aluminum extrusion and is not enclosed in a lighting tube, so that a user is often subjected to electrical shock due to unexpected touch with the heat dissipater in replacing a lighting tube, leading to hazards. Thus, the present invention aims to provide a structure of lighting device that improves the convenience of use of lighting device.